Is it actually preventing you from sewing after you see the "error" message? Is it just a picture of the feed dogs that you are seeing? If it is, and it's like my Janomes, it's just reminding you to put the feed dogs down. If you've got them down and your stitch length is at zero then you should be good to go. Make sure to turn the handwheel to check the needle doesn't hit the foot before you speed ahead. This can happen if you were using zig zag or a decorative stitch before FMQing.